Valve for wireless telegraphy or telephony



April 10, 1928.

Filed July 13, 1925 Patented Apr. 10, 1928.

UNITED STATES PATENT OFFICE.

JACQUES ANTOINE MARIE HAWADIER, or PARIS, rRANcE.

Application filed July 13, 1925, Serial No. 43,259, and in France August 2, 1924.

My invention relates to a valve of the kind used in wireless telegraphy or telepl 1ony, specially constructed with the ob ect of utilizing alternating current from the town su ply to heat the cathode.

ith this object in view the single filament generally used in triode valves is substituted according to my invention by a tubular cathode the heating of which is ensured by the action of a central auxiliary filament branched upon the alternating current from the town supply. In order to avoid all contact of this auxiliary filament with the tubular sending cathode, the latter is mounted and supported upon a tubular part of refractory and insulating material. The cathode is moreover specially constructed with the object of ensuring a regular transmission.

The invention has further for its object a special mode of supporting the auxiliary filament and the tube carrying the cathode.

The appended drawing shows by way of example two difierent modes of construction of a valve made according to the present invention.

Fig. 1 is a diagram showing the general disposition.

Fig. 2 shows separately the special supporting device for" the auxiliary filament and the cathode tube.

As will be seen the valve consists of a tubular cathode it carried upon a part also of tubular shape I) made of a refractory insulating and homogenous material such for instance as quartz. The cathode a which is designed for the sending off of electrons is constituted by a tube made of a metal such as tungsten or molybdenum acting as carrier for a layer of active substances capable of emitting at moderate temperatures or in the body of which the active substances are incorporated or mixed. The oxides or oxide mixtures studied by Wehnelt such for instance as calcium, barium, strontium or thorium oxides, etc., may be employed advantageously to constitute the active substances. The cathode is connected to the plate and grid circuits by the lead 0.

. The cathode formed in this manner is. heated by a straight or helical auxiliary filament 0?, as shown, the emissive power of which in addition to that of the cathode will bring the latter to a degree of heat suflicient to produce an abundant emission of free electrons. The filament d will be branched on an alternating current, such for instance as the circuit of the town sup-. ply, by means of leads 0 and 0 The insulating cathode support I) is kept centered around the auxiliary filament d by means of tubular parts f and f of nickel for instance secured by pinching upon the leads e and 6 these tubular parts serving thus to retain both ends of the auxiliary filament d in position. This arrangement has also for its object. to enclose the central auxiliary filament in order to avoid a prejudicial emission of electrons b the latter.

The valve is completed in t e usual manner by a grid 9 and a plate It connected with their respective circuits by the leads i and j.

In the mode of execution shown in Fig. 2 the cathode is placed horizontally. The auxiliary heating filament d secured to the leads 6, e is wound helically-for part of its length only and in the middle in order to allow of heating the middle part of the quartz tube without putting the admissions of current in the interior of said tube. The latter is carried by means of supporting sleeves k, k which are fixed by soldering to the current admissions and contribute to the cooling of the extremities of the quartz tube. The sleeves k are made of a refractory metal such for instance as molybdenum.

The cathode being formed by a rigid undeformable part it will be possible to bring the grid and plate nearer together without any risk of producing a short circuit caused by electrostatic attraction.

In the course of manufacture the occluded gases are completely evacuated from the difierent parts of the valve and newssary care should be taken during the pumping in order to avoid any formation of gas which might be prejudicial to-the working of the valve. 1

I claim:

1. A valve for wireless telegraphy and telephony, comprising a metallic tubular cathode coated with electron emitting metallic oxides, an auxiliary heating filament in said cathode, conductors for supplying alternating current supporting the filament, a quartz tube between the filament and cathode, supporting the latter and projecting beyond the ends thereof, and collars at both ends of the quartz tube supporting the same and the said conductors. I

2. A valve for wireless telegraphy and telephony comprising a grid, a plate, a tubu- UED lar cathode coated with electron emittin said filament and "su porting the same, nickel oxides, an electrically non-conductin an; collars supporting t e ends of said tube and heat transmittingtube longer than. sai cathelectrically connected to said conductors and 10 ode supporting t e latter and pro'eeting been ported thereby.-

' I yond its ends, a. spiral heating ament in n testimonyfthat I elairn the foregoing as said tube solely in the middle part thereof, my invention; I have signed my name. alternating current supply conductors forv JACQUES AN'l'lJlNE MARIE'HAWADIER. 

